Prior latching mechanisms have included a simple latch which rotates about a single pivot, tracing a circular path on the mating surfaces. In operation the prior capture latch would be maintained in an engaged configuration by a biasing means, such as a torsional or tension spring. As the leading surface of the mating docking mechanism contacted the capture latch, the latch was depressed until the mating surface of the mating docking/berthing mechanism came into cooperative alignment with the capture latch. The capture latch then resumed its engaged position and engaged the mating surface, thus preventing withdrawal of the mating docking/berthing mechanism. It can be appreciated that at least two substantially opposed capture latches would have to be so engaged to secure the two docking/berthing mechanisms in place together, to achieve stabilization of the two vehicles, relative to each other and allow structural connection.
Should one side of the docking/berthing mechanism not fully seat, the opposing latch is required to release or not trap the docking/berthing mechanism in order to allow another attempt at docking/berthing. The prior capture latches were not easily released under these circumstances since the load would be on the latch and the frictional component of the load opposes the releasing force direction. Thus, it is often necessary to relieve the load before the latch can be released by causing a gap between two opposing surfaces.
In a similar fashion, the release of the fully seated docking/berthing mechanisms for separation of the spacecraft is not facilitated by the prior capture latches because of the load on the latches and the resultant frictional component.
A vector sensitive latch is described in U.S. Pat. No. 3,820,741 and this latch was used in the Apollo-Soyuz Test Program docking/berthing system. That system incorporated three latches fastened to a docking/berthing ring and automatically released if the mating ring was not fully captured and separated by a set amount. In the fully captured condition, a small clearance between the latch roller and the latch would set. Structural latches were thus provided to remove the clearance and to preload the mating rings in order to prevent separation. Not only was a second set of latches required but in addition means to activate and release the second set of latches thus incorporating additional unnecessary weight and complexity to that particular system.